[Elecraft] KPA-100 under test

[Bob Henderson]

Hi

I was one of the lucky ones who got to bring back a KPA-100 kit from Dayton.
The kit is assembled and currently under test.  However, I have hit a snag
and would appreciate a bit of help.

Testing so far has progressed to Page 46 - Fan Test routine.

The fan does not operate with fan mode set to either FAN LoHi or FAN Hi.
The fan itself is ok as it operates briefly when the K2 is powered up.
Looking at the cct diagram on page 62 it is apparent that U2 pin 11 (/out 7)
should be low to drive the fan at low speed and U2 pin 12 (/out 6) should be
low to drive it at full speed.  These signals are both unconditionally high
on my KPA-100.  Outputs RC7 & RC6 from U1 are required to go high to operate
the fan at low/high speed.  These outputs are both unconditionally low.  U1
& U2 are otherwise operational as my low pass filter switching is operating
correctly.  My fault finding has ground to a halt at this point as I don't
know what input is  required at U1 to turn the fan on.

Can someone point me in the right direction please?

Many thanks.

Bob 5B4AGN